Rotary kiln



June 22, 1937. H.- c. THAYER ROTARY KILN Filed March 7, 1936 4 Sheets-Sheet l I INVENTOR:

H aura/wk C d W Kim 33 I ATTORNEYS.

H. C. THAYER June 22, 1937.

Filed March 7, 1956 4 Sheets Sheet 2 June 22, 1937. H. c. THAYER 2,084,713

ROTARY KILN Filed March 7, 1956 4 Sheets-Sheet 3 INVENTOR) W C 'TW KMV RQMJ M 1/ A. TTORNEY15 June 22, 1937.' H. c. THAYER 2,084,713

I I ROTARY KILN Filed March '7, 1936 4 Sheets-$heet 4 INVENTK )R? Fm sno rfilaww, K mw WE ATTORNEYS.

Patented June 22, 1937 PATENT OFFICE ROTARY KILN Howard C. Thayer, Jersey City, N. J., assignor to Quigley Company, Inc., New York, N. Y., a corporation of New York Application March '7, 1936, Serial No. 67,633

19 Claims.

This invention is a novel rotary kiln. It relates especially of that class of kiln, oven or furnace having an elongated cylindrical or tubular chamber inclined downwardly from the infeed toward the discharge end and rotated to cause the movement, exposure and progress of the materials being treated; and with means providing heat or cold so that the apparatus is adapted for the drying, roasting, burning or other heat-treat- 1 ing or cooling of various industrial raw materials, mixtures or products, as well asperforming the mechanical actions of reducing and mixing the materials, and various chemical reactions, all occurring progressively or in sequence as the materials traverse the chamber.

Such apparatus is available for a wide extent -of industrial use in the processing ofv different kinds of materials. A typical instance is the treatment of materials, as clay, or mineral colors, subjected to temperatures up to 900 F. more or less, to dry the materials, which are reduced to a relatively flne condition in the chamber, by tumbling, impact and abrasion, sometimes preparatory to subsequent grinding and final reduction of the product. The character of the refractory lining of the kiln determines the temperatures which may be used; higher temperatures therefore being available with proper lining material; and as already stated the apparatus may be used for chilling treatments. The raw materials may be supplied to the apparatus in bulk condition, sometimes lumpy, or they may be fed gradually to the kiln, after preliminary reduction and may be subjected to temperatures sometimes much higher'than that mentioned. Such tubular furnaces are useful for various other purposes involving mixing or dehydrating of materials, or chemical or metallurgical treatment; and the tubular chamber may be of various sizes as from 6 to 12 feet in diameter, more or less, and of lengths running to 50 or 100 feet, more or less; with speeds as low as a fraction of a turn or as high as several turns per minute, d eapending upon diameter and purpose. 5 A general object of the present invention is to improve the efllciency of operation and treatment of materials in a rotary kiln of the class referred to as compared with the many forms of rotary kiln heretofore industrially used. Particularly it 50 is an object to promote efficiency by improving the mechanical handling'of the materials within the kiln to increase their exposure to the high or low temperatures or-.other-treatment, permitting a greater rate of output; also to promote 55 economy by conserving heat and utilizing it to best advantage; also to conserve power and to increase efficiency and rapidity of heating or cooling.

Another object hereof is to increase the durability and life of a rotary kiln of the type comprising a metal or steel shell or drum with refractory or firebricklining, namely, by a novel construction and arrangement ofrefractory elements or blocks. Particular objects are to afford simplicity of structure by requiring a minimum number of lining block shapes; to afford ease of manufacture and assembling of the parts of the kiln, with efllcient keying or interlocking of the blocks or shapes; and a resulting strong and unitary assemblage of shell and lining elements. A special object is to afford a lining formed with pocketsfor the lifting and showering of materials of kinds not liable to clinkering or clogging in the pockets, which structure is simple, rugged, durable and effective.

A further object is to afford an optional mode 20 of applying heat, for the drying and other treatments, namely, in an indirect manner, thus protecting the treated materials from the gases of combustion and substances entrained therein. Other and further objects and advantages of the invention will be explained in the hereinafter following description of several illustrative embodiments thereof, or will be understood by those conversant with the subject. To the attainment of such objects and advantages the present invention consists in the novel rotary kiln, and the novel features of operation, combination, arrangement and structure herein illustrated or described.

In the accompanying drawings Figure 1 is a side elevation of a rotary kiln with tubular chamber embodying the principles of the present invention, the body of the rotary portion being shown in central vertical section, looking leftward in Fig. 2, and being broken away at two points in its length to condense longitudinally the illustration.

Fig. 2 is a left elevation of the rotary chamber taken generally in section on the section line 2-4 of Fig. 1, but partially broken away in section on the line 2 2 of Fig. 1, and at another point on the line 2 -2 of Fig, 1.

Fig. 3 is a perspective view of a few rows of lining blocks assembled as they would be in the kiln, this figure introducing certain'modiflcations of structure, namely omission of dowels and insulating inserts.

Fig. 4 is a perspective view of a pair of adjacent lining blocks of the Fig. 2 form and constitutin the chamber. Fig. 5 is a left elevation of a block-pair of modified form, with square dowels but no inserts;

and Fig. 6 is a similar view of a. further modification, with extra dowels.

Fig. 7 is a vertical section view similar to Fig. 1 01. the discharge end of a modified structure of rotary kiln, providing indirect or radiant heating of the treated materials.

Fig. 8 is a right elevation and section on line 8-8 of the structure shown in Fig. 7.

Fig. '9 is asection on line 9-9 of Fig. 12 showing the relation of the pocket wall to the web,

' sive tiers of lining blocks. .1

'' indicated in Fig. 11.

Fig. 13 is a view like part of Fig. 3 showing a monolith structure, without division into blocks.

Figs. 14 and 15 in views like Fig 5 show two modified structures of block each requiring only one block per pocket. 4

Fig. 16 is a detail view corresponding with part, of Fig. 2 and showing more fully the manner of cementing together adjacent blocks.

The general figures show'the cylindrical outer shell or drum 20 composed preferably of sheet steel, or highly refractory ferrous alloy, set at an incline, and carrying at two or more points exterior ribs or tires 2| by which the weight of the apparatus is supported upon a system of bearing rolls 22 carried on standards,23, all in conventional manner. An external gear 25 is indicated, representative of any means of power driving the rotary chamber, for example from an electric motor, through reduction gearing. In the case of a kiln about 6 feet diameter and 50 feet long, the speed may be one rotation in 10 seconds, more or less.

At the high or ini'eed end of the kiln is shown a stationary head or hood 21, adjacent the inner, wall of which the end of the drum turns, the head being shown mounted stationarily on a base. An infeed mechanism or device 28 is shown which may be of conventional regulable type, with outer hopper receiving the material and interior spout 23 delivering into the rotary drum or chamber through the head 21 as shown. The hot gases traversing the chamber from the low discharge end to' the high infeed end pass thence into the head 21 from which they may be conducted by. a fiue 30 to 'a stack, blower or other means of maintaining suction draft and flow through the apparatus. The gas flow is shown counter to the progress of the solid material, but may in some cases be in the same direction. As already stated, a chilling treatment may be efiectedby using cool air rather than hot gases. The head 21 may have a manhole with cover 3| giving accessto the kiln. The heads are shown stationary in Fig. l, but may be bodily shiftable from the rotary elements as with the discharge head 32a A dust collector may be inserted if desired in the fiue 30 or elsewhere. Air vents 35 may be suitably provided.

At the low or discharge end is shown a station- I This may be of conventional type.

my head 32. The two heads 21 and 32 may have the usual sort of closure or packing between the heads and the rotary shell, to exclude the passage of air or gas;

I the second zone.

7 9,084,718 1 L a structural unit in the third or lowest zone of or in some cases it may be desirable to admit leaving a suflicient opening for the admission of supplemental air. The arrangement may be such as to allow for expansion of the shell when heated, and contraction thereof when cooled. The treated materials af ter traversing the rotary chamber may pass from the chamber into the head 32 and thence drop into a pit or pocket 33,

in which is indicated conventionally a screw conveyor 34 as a means of progressively removing the accumulating material from the apparatus vwhile preventing uncontrolled ingress of air.

Heating for the rotary kiln may be provided in various ways, ,for example by the hot gases from a burner 36 as shown; or the heating may be indirect, avoiding contact between the products of combustion and the materials being treated, as in Figs. '7 and 8 later explained; or the'hea'ting may be by electric heating means. In any case the heating of the materials is preferably effected by radiation within the chamber. As already indicated the apparatus may be used for cold treatments, by extracting heat, directly or indirectly, and the extracted heat utilized for any desired purpose. 7

The burner 36. in Fig. 1 produces and injects flames directly into the rotary chamber, thus providing radiant heating, as well as heating by as oil,'gas or pulverized coal,

Figs. 1 to 3 the chamber space is indicated as dividedinto a succession of zones F42 and 43. The first or initial zone 4i at the high end of the chamber, receives directly the'materials from the i-nfeed device 28, 29. This zone is shown as having a plain cylindrical interior surface "the material sliding and tumbling in the zone and at the same time progressing along the downward incline to The heating up and drying commence in the first zone and are continued in the second or middle zone 42, having a special construction of projections or. ribs for more ef- 'fective tumbling, mixing or exposure of materials. The third or final zone 43 is at the low or dis,- charge end of the chamber and as will be described is constructed vith a system of pockets or buckets arranged to pick up the material from the pool thereof resting at the bottom and to distribute and shower the same downwardly throughout the entire volume of the chamber. The respective zones may have diiierent extents of length in the complete structure.

The refractory lining for the zones as thus described is made up of lining blocks or elements of several difierent shapes as will now be described; each of the blocks having an arched or curved shape, its outer surface preferably conforming with the curvature of the steel shell 20 and the inner surfaces of the several blocks presenting a generally cylindrical boundary to the interior space hr volume of the chamber.

In the first zone the lining may be built up of substantially plain blocks 45, shown in Figs. 1 to 3 and separately in Fig. 6. These present an unbroken interior chamber surface. In the second zone is shown a mixture (of plain blocks 45 and other blocks 45 having projections or ribs 41 adapted to agitate, lift, and tumble the material traversing this zone. As shown in Figs. 1 to 3 every second block in the middle zone is a ribbed block, the ribs being arranged in alinement, constituting a seriesof substantially continuous ribs through this zone. Four or six ribs altogether may be enough. All blocks are wedge shaped, as in an arch, thus confining each other, except against endwise assembling or removal.

In the third ,zone, which might carry some plain blocks, there is shown a system of pocket forming blocks 48 and what may be described as filleted blocks 49 providing a curved entrance to each pocket. As-Flg. 2 shows 13 of each of these 15 ,rshapes, 13 pockets are provided, and no plain blocks are shown. Each pocket block and adjacent fillet block constitute a pocket-forming unit, shown separately in Fig. 4, which unit might be constructed in a single integral block, except that, for purposes of manufacture, they are constructed more easily and efliciently as separate blocks, assembled as shown.

At the time the various blocks 45 to 49 are assembled within the outer shell 20 they are preferably coated, at their meeting edges, with a layer of refractory or high temperature cement 51, as indicated at Figs. 2, 3, 5 and 6, and in detail in Fig. 16, thus firmly uniting the system of blocks as a unitary whole.

According to a particular feature of this invention the 'firebrick lining blocks are not merely assembled and cemented, but are keyed and interlocked with each other by a system of dowels 52, which may be formed at the time of erection, the several blocks being provided with dowel receiving grooves 53, or rather half grooves, falling into register and. providing an interlocking recess or groove. While the dowel recesses or grooves might be discontinuous and still aiford keying and interlocking functions, preferably the grooves are continuous, running in factin the assembled structure the entire length of the chamber, or of each zone thereof, so that the dowels constitute also a sealing means making the lining gas-tight and preventing travel of gases between the blocks either outwardly or inwardly.

According to the preferred form of this invention the dowels 52 occupying the grooves or recesses 53 are composed of refractory cement, preferably the same as the cement 5| which is plastered on the meeting faces of adjoining blocks, as shown in detail'in' Fig. 16. To carry out this construction the dowel grooves might be filled with the cement just before the positioning of each block; but a preferable system is to assemble each pair of adjacent blocks with the grooves empty, and then force the plastic cementing material into each groove, as by a form of cement gun, reachedinto the groove and withdrawn pro- 6Q gressively as the discharged material fills the groove. A suitable high-temperature air-setting plastic cement adapted to the uniting of the blocks and the filling of the dowel grooves is that commercially known as Hytempite, which also is well adapted to be blown or shot into place by a jet or gun as described. Other dowel materials shown in Fig. 2 by the provision of an insulating segment or insert 54 occupying the outer portion of each block, but limited circumferentially so as not to disturb the contact of each block with blocks in the shell.

the block at the time of molding the latter out of flrebrick, or subsequently inserted in the back recess 55 before or at the time of assembling the The insert 54 is of a material having a greater heat insulating capacity locking dowels 52, shown in Fig. 2, are for convenience omitted from-Flg. 1, but they or the grooves receiving them are shown in Figs. 4, 5 and 6. In Fig. 5 certain of the dowels are positioned nearer to the center of the blocks than in Figs. 2 and 4, where this is permitted without weakening the structure. The dowels may be round as generally shown, or square or other form as shown in Fig. 5, and in Fig. 6 where there are no pockets an extra row of dowels 25 is indicated. The back insulation inserts 54 are not always necessary and are omitted from the disclosures of Figs. 3 and 5.

Coming now to the special blocks 68 and 49, cooperating as a unit, and forming a pocket for the lifting and spilling of the material in the chamber, these may be described as follows. Each block has an inner face, toward the chamber space, and an opposite outer face against the shell. Each block has opposite side faces, each side face of block 48 in contact with a side face of block 49, and so on around the periphery. Each block has opposite end faces, each contacting with an end face of another similar block, assuming that the blocks are lined up regularly, although manifestly each annular series of blocks might be circumferentially displaced as in Fig. 12 with relation to the adjacent series, giving a more thorough showering;

' With this basis of description the pocket block 48 may be designated as formed with an interior material-lifting and spilling pocket or space 60, bounded at its inner side by an extension or wall 6|. The wall 6| encloses the pocket '60 at the chamber side, and near its extremity or lip it is preferably shaped with a projection 62, extending away from the chamber and providing av slight neck or contraction to the pocket space. As clearly appears in Fig. 4 and others the pocket is open and accessible at one end of the block, whereas at the other end the pocket is closed by a continuous web 63, separating each pocket from the corresponding pocket in the next endwise adjacent block. The projection or lip 62 is'of value in the action of distributing the shower of material across the entire width of the chamber, as will be explained. i

The fillet block 49 has a cooperative shape, comprising a cutaway inner surface 65 forming a curve, entrance or fillet by which the material may freely and smoothly enter-and leave the pocket 60. This entrance or space 65 may be designated the mouth of the pocket. As with the pocket block, the fillet block is formed with a web 61 at one end, alining with and contacting the web 63 of the pocket block, as well shown in Fig. 4. Each pocket and mouth, contained in the joined blocks 48 and 49, is thus a separate element, independent cf the similar-pockets formed in other pairs of similar blocks.

The system of pockets thus described, extending both circumferentially and longitudinally aflords an eflicient means of lifting and showering the material substantially throughout the volume of the chamber. The pockets, are substantially interior of the refractory lining ,and each pocket scoops up and lifts a portion of the material, spilling it little by little as the pocket travels around the upper half circumference. 0n Fig. 2 is indicated a pool of the material to be treated, and several pockets are passing through the pool and becoming filled with material. As each pocket rising at the left. passes the horizontal diameter it commences to spill or discharge maafforded maximum exposure to treatment.

The structure is quite strong and rugged. The

pocket-forming wall 6| might be subject to injury at the open end, seen in Fig. 4, but this is herein prevented by the fact that this end of this wall is cemented firmly to and becomes substantially an integral part of the web 63 of the next adjacent block. The web 63 on the pocket block 48 and the web '61 on the fillet or entrance block l9 are cemented together in alinement and form a substantially continuous web, strengthening and protecting not only the pocket and mouth in the blocks carrying the webs, but also in the next adjacent blocks cemented thereto. As a matter of structure, it is to be understood that while. the webs 63, 61 are provided integrally at one end of the blocks 48 and 49, the webs might be at a middle point thereto to the same effect, as in Fig. 10.

In Fig. 2 the webs 63 and 61 do not extend inwardly toward the chamber to thesame extent as the walls 6i forming the pockets, these walls therefore projecting slightly from the general cylindrical surface of the lining. In Figs. 3, 4 and 5 however the webs have been extended so that their inner surfaces are in cylindrical al-inement with the walls 6|. This constitutes a considerably stronger and more durable lining structures With the extending of the webs the blocks 49 are correspondingly extended, and the concave surface 65 somewhat reshaped to constitute an effective mouth or entrance to the pocket space.

In operation the partly reduced clay or other material, entering the first section or zone 4lof the kiln becomes hot, losing much of its moisture and volatiles, becoming harder and more finely reduced. Being tumbled in the second'zone or section of the kiln the material is more effectively dried and is reduced to a still greater extent. When it enters the'pocketed zone or chamber 43 -it is in proper condition to be picked up and showered down by the pockets, as already explained. Throughout its travel the material is raised to higher and higher temperatures, and in the final zone the material receives heat not only from the heating source or flames, but also from the walls of the pockets, which themselves have received much radiant heat; the material therefore not cooling off but being maintained hot while being engaged, lifted and spilled by the successive pockets.

In rotary kilns the successive beatings and coolings of the apparatustend to cause expansion diiferences between the metal ell and the refractory lining, the usual effect of which has been to open the joints between the lining members and sometimes to break the bonds thereof, thus objectlonably admitting gases or dust to the chamber. With the present invention the solid from the outer shell is accomplished without introducing disadvantages. The insulating material need not be of a strong character, but is a porous refractory, and may even be crumbly. It is so placed, in a recess, that it takes no strain, and leaves the blocks of full strength. Indeed the blocks contacting the shell only near their outer corners afford an improved fit between the blocks and the shell. The insulating material mentioned may have about one quarter, more or less, of the conductivity of the firebrick of which the pocket blocks are preferably composed. In some cases the described wall can be constructed with the pocket blocks 480i one material, as ordinary fire-brick but with the blocks 4 5 and 49 composed wholly of insulating refractory. ,The

extensive insulation between-the chamber and the shell not only protects the latter and conserves-heat, but affords a greatly reduced period of initial heating of the kiln.

While the described lining is composed of a great number of relatively small blocks it is to be understood that considerably larger units might be preformed and assembled to afford the same structure. The lining might even constitute a monolith, for a substantial length of chamber, as shown in Fig. 13 molded within the shell, with wooden or other cores determining the pockets, adapted tobe burned out.

Although certain materials have been mentioned for the lining blocks, it is not intended to limit the invention thereto, and various refractories may be used. Thus, for insulating inserts or blocks there may be used a porous refractory, as Insulbrix, preformed as blocks and burned. Unburned refractories also may be used, such as the plastic artificial materials "Hearth-Crete or Cast-Refract, which may be cast or molded directly in the kiln, and which set, forming a monolithic lining; and for heat insulating such a monolithic lining can be made from Insulcrete. These materials are known on the market by these names, and still others of analogous character may be employed.

In the modification shown in Figs. 7 and 8, the materials under treatment are heated only indirectly, that is, by radiant heat, whereby the materials are isolated from the fuel and; flame, gaseous products and dust being excluded from the treating space. Certain elements correspond with the other figures. The enclosing metal shell .20,terminates 'at' the discharge end, beneath which is a pocket 33 wherein is a conveyor 34 removing the treated material. The shell is lined with refractory material composed of pocket blocks 48 and fillet blocks 49, with cement dowels -52 between them, or between certain of them.

Each block 48 provides a material receiving pocket 80 and each block 49 provides a mouth 86 to the pocket, this arrangement affording a spilling or showering action as already described.

' The structure of Figs. 7 and 8 differs from the other embodiments in several respects. The refractory lining terminates short of the discharge end of the'shell, and. the shell carries an interior flange 1| confining the end of the lining. 10 At the extreme end of the shell is a circular plate 12, substantially closing the kiln at this end. Between theflange II and end plate 12 is a space which may be considered as a rotary head, the.

' shell in this space having s; peripheral series of 15 holes I4 by which the completely treated mate-,

rial may be dumped from the head into an exterior chamber 15 shown as of annular form, constituted bya wall I8, which wall is continued as the receiving pocket 33. It is sometimes desirable to provide for the heating of the refractory lining, and for this purpose every second dowel 52 is shown replaced by a heating tube 18. These may constitute flretubes and at the same time serve as dowels or keys for the maintaining of the lining blocks in position. I

For radiant heating of the materials there is shown a group of flretubes '88, suitably suspended or centrally mounted in the kiln chamber. These are shown plain but may have projecting sur faces or flns of any form to increase substantially the heat radiating surface. the firetubes l8 and 88 are shown supported in the end plate [2. In the case of a long kiln the tubes 80 maybe suspended by spiders at other points in the length .of the apparatus, and at the far or infeed end the flretubes may all discharge into a head leading to the flues and stack as already described. As it is usually desirable to maintain a regulated flow of air or gas through the treating chamber there is shown, mounted on the end plate 12, a damper ring 82 having damper holes may all be heated by fluent fuel, as gas, and a gas burner 88 is shown directed into each of thehtubes, producing flames traveling through the tubes. Allof the burners 88 are' shown as fed with an air-gas mixture from the mixing chamber 81, which rotates with the tubular chamber. By means of a packing 88 the mixing chamber is connected with a supply pipe 89 which is supplied by gas through pipe 9| under valve regulation and by air through pipe 92 also .60 under regulation. The suspended firetubes 88 "may be mounted in various ways but are shown rotating relatively with the kiln, this arrangement being simpler of construction and tending to prevent accumulationof material upon the 65 iiretubes. r

The hot gases or flames traversing the lining tubes 18 keep at a suitable temperature the lining blocks and especially the walls of the pockets 68, preventing adherence of material thereto. The tubes 80 become red hot and radiate at a high rate to the material showering through the chamber and to the pool of material held' in the bottom of the chamber, and as well to the lining of the chamber; thus affording The ends of an effective heating, drying and treating of the material being handled.

Regulation of the firetube action may be afforded by controlling the combustible mixture and the speed of travel of the flames through the tubes. Thus when the combustion gases travel at relatively high velocity, or when the combustion is relatively slow, the heating action is extended and thus adapted to maintain highly hot the radiant tubes from the burner end clear to the infeed end of the chamber. When the mixture is such as to afford faster combustion, or when the combustion travel is relatively slowed down then the highest temperature is provided at the ignition end of each tube, usually near the discharge end of the kiln, the tubes being relatively cooler at the infeed end. Preferably in the lining tubes 18 the combustion is relatively slow so as to maintain the lining and the pockets relatively hot throughout the length of the kiln.

Fig. 11 shows a modified kiln as to discharge end structure. The shell 28 has welded interior rib or flange H as before, but now a refractory special end block 94 is provided engaging the flange, the lining blocks 48 abutting it. The shell 20 is shortened and does not enter the head 82. 95 depending substantially to the inner wall of the head. The block has a groove 96 fitting over the flange II. An annular series" of blocks 94 lines the end of the shell; one such block being recessed to the end of the shell, one such block being recessed to the line!" to constitute a key block\to facilitate assembling. The head has a bottom delivery chute or pocket 33 ."For access to the shell the head is bodily retractible,

having carriage wheels or skids 98 running upon rails 88.

The invention may be described as a rotary kiln of the class having a cylindrical shell with refractory lining enclosing a chamber through which advances the material under treatment and having means for applying heat to the advancing material, with various general and special features of improvement as described. By way of explaining .the terms used in certain claims it may be stated that the system of interior pockets provided in the lining at the third zone-constitutes a feature which may in some cases be extended to the full length of the kiln, especially where the material has been pretreated in preparation for the action afforded by the pocket system. For each pocket the lining may be said to comprise awall 6| which is exposed to the chamber heat, and behind or outwards of which the pocket recess extends. By this arrangement and the lip 62 an ample pocket space is provided, and yet the proper distributing of the showered material across the entire sectional volume of the chamber. webs 63 are integral and separate each pocket from the next endwise adjacent pocket. The blocks 48 and 49 constitute a pair or unit, and might be integral, as in Figs. 14 and 15 or separate as in Figs. 2 to 6 this unit shaped to afford the described pocket and its mouth or entrance 66. Each such unit has a reenforcing and {pocket closing web .co-extensive with .the area 'of the pocket, this web preferably at one end of the pocket in each block or unit.

There have thus been described several illustrative embodiments of the invention, and the operation thereof. Since many matters of operation, combination, arrangement and structure 'may be variously modified without departing The block 94 has a drop flange or apron The from the principles of the invention it is not intended to limit the invention to such matters except to the extent set forth in the appended claims.

I claim:

1. A rotary kiln of the class having 'a. cylindrical metal shell with a refractory lining enclosing a chamber through which advances the material under treatment, the lining, in at least one longitudinal zone of the chamber, being formed with a system of interior pockets to lift the material and shower it through the sectional volume of the chamber, subject to the treating action, and such lining being composed of generally wedge-shape refractory blocks closely asembled and keyed andinterlocked with each other by a system of dowels, the dowels extending longitudinally of the length of the rotary kiln, and the blocks being formed with complev mentary longitudinal recesses occupied by such dowels.

#2. A rotary kiln of the class having a cylindrical shell with refractory lining enclosing a chamber through which advances the material under treatment, the lining being composed of a system of refractory or flrebrick blocks assembled face to face within the curved interior circumference of the shell, and the contiguous faces of circumferentially adjacent blocks having preformed complementary longitudinal grooves forming dowel spaces, and a refractory cement filling in each such dowel space introduced while plastic and set after assembling, thus forming a dowel adhering to the blocks and positioning 5 and interlocking them and constituting a seal against penetration of gases or dust.

3. A kiln as in claim 2 and wherein the cement which occupies the dowel spaces between blocks is extended also as a layer between the faces of the adjoining blocks.

4. A kiln as in claim 1 and wherein the dowel recesses between each pair of blocks comprises complementary grooves extending longitudinally.

and alined with corresponding grooves between other pairs of blocks whereby the inserted dowel forms a continuous dowel through a substantial length of lining. I

5. 'A rotary kiln of the class having a cylindrical metal shell with a refractory lining and enclosing a chamber through which advances the material under treatment, the lining, in at least one longitudinal zone of the chamber, being formed with' a system of interior means to lift the material and shower it through the sectional 55 volume of the chamber, subject to the treating action, and such lining being composed of generally wedge-shape refractory blocks closely assembled and keyed and interlocked with each other by a system of dowels, adjacent blocks being .fi liormed with complementary preformed longitudinal recesses occupied by such dowels, and the dowels consisting of high-temperature refractory air-setting cement forced into such recesses after assembly of blocks and there set into adhering union with the adjacent blocks.

6. A rotary kiln of the class having a cyli'n.-. drical shell with refractory lining enclosing a chamber through which advances the material 70 under treatment and having means for applying heat to the advancing material, the lining being composed of a system of flrebrick blocks, having outer recesses and block extensions bearing on the shell between such recesses, and with molded and set insulating refractory inserts in such reand ceases partly to insulate the blocks from the shell.

'7. A rotary kiln as in claim Band wherein such inserts consist of cellular-type molded re-. iractories occupying such recesses.

8. A rotary kiln as in claim 6 and wherein such inserts consist of preformed refractory bodies set in such, recesses during production of such blocks and therefore permanently fixed in place. l0

9. A rotary kiln of the class having a cylindrical shell with refractory lining enclosing a chamber through which advances the material under treatment and having means for applying heat to the advancing material, the lining, for at least 15 part of the length of the chamber,-being formed with a system of interior pockets to lift the material and shower it through the chamber subject to the heating action, the lining comprising, for each pocket, a wall facing the chamber inte- 20 rior and enclosing the pocket behind it, and the extreme edge of such pocket wall beingshaped away from the chamber forming a lip extended into the pocket space and contracting the pocket neck; whereby each pocket operates to release 25 and shower the material across substantially the entire sectional volume of the chamber.

10. A rotary kiln of the class having a cylindrical shell with refractory lining enclosing a cham ber through which advances the material under 30 treatment and having means for applying heat to the advancing material, the lining being composed of refractory blocksfand for at least part of the length of the chamber, having such blocks formed with a system of interior pockets to lift the material and shower it through the chamber subject to the heating action, the lining. comprising, for each pocket, a wall facing the chamber interior and enclosing the pocket behind it, and the extreme edge of such pocket wall being shaped 40 away from the chamber forming a lip extended into the pocket space and contracting the pocket neck; whereby each pocket operates to release and shower the material across substantially the entire sectional volume of the chamber.

11, A kiln as in claim 10 and wherein for each pocket the blocks comprise a block pair, one enclosing the pocket interior space and the other forming a tapered entrance or flaring exit to the pocket.

12. A kiln as in claim 10 and wherein the blocks forming each pocket are formed with end webs and are cemented to the blocks of the next longitudinally adjacent pocket whereby such webs strengthen the blocks of both pockets. Y

13. A rotary kiln of the class having a cylindrical shell withrefractory lining enclosing a chamber through which advances the material under treatment and having means for applying heat to the advancing material, the lining, for at least part of the length of the chamber, being formed with a system of interior pockets to lift the material and shower it through the chamber, subject to the heating action, a system of heating tubes enclosed in the refractory lining and reinforcing the same, and means for interiorlyheating such tubes, to maintain hot the lining and the pockets therein.

14. A rotary kiln as in claim 13 and wherein the shell lining is built up of refractory blocks and the heating tubes act as means to key and position the blocks in the lining.

15. A rotary kiln of the class having a cylindrical shell with refractory lining built up of refractory blocks and enclosing a chamber through MM?! which advances the material under treatment and having means for applying heat to the advancing material, a system of heating tubes enclosed in the refractory lining and reinforcing the'same, and also keying the blocks to each other, and means for interiorly heating such tubes, to maintain hot the lining and the pockets therein.

16. In a rotary kiln of the class having a cylindrical metal shell with a refractory lining composed of refractory blocks; and enclosing a chamber through which advances the material under treatment, a construction for the discharge end of the kiln comprising an interior annular flange projecting from the shell near its discharge end, and the lining blocks comprising an annular series of blocks near the discharge end formed with grooves receiving such flange and formed with an outward extension or apron over which the discharge takes place at the lower part of the kiln.

1'7. A rotary kiln oi the class having a cylindrical shell with refractory lining enclosing a chamber through which advancethe reduced solid materials under treatment, comprising, in combination with said shell and lining, a system of flretubes for applying heat to the advancing materials, said firetubes being suspended within.

the chamber spaced well away from its lining, and said lining being formed with a system of pockets adapted to lift the reduced materials and shower them across the chamber occupied by said suspended tubes, and means for interiorly tiring such suspended tubes to radiant temperature during rotation of bin and showering of materials, thereby to heat radiantly the materials.

18. A rotary kiln of the class having a cylindrical shell with refractory lining enclosing a chamber through which advance the finely reduced solid materials under treatment. comprising, in combination with said shell and lining, a system 0! tiretubes for applying heat to the advancing materials, said flretubes being suspended within the middle part of the chamber away from said lining and materials, and said lining being provided with means adapted to lift the materials and shower them across the chamber occupied by said suspended tubes, and means for interiorly firing such pended tubes during rotation of kiln and sho ering oi materials.

19. A rotary kiln as in claim 18 and wherein the tlretubes are adapted to be heated to radiant temperatures for heat radiation downwardly to the materials under treatment and upwardly to the lining, and the kiln is provided with means for maintaining flow of air or gas through the chamber and showering materials outside of the ilretubes, whereby the showering materials are treated simultaneously to such radiant heat and to the action 01 such air or gas.

HOWARD C. 'I'HAYER. 

